Posted: Thursday 15th November 2018 by Edwin-Malins
Hornbeams in Sydenham Hill Wood - Daniel Greenwood
In a blog exploring the autumnal Great North Wood, project officer Edwin Malins celebrates a wonderful time of year to discover this ancient landscape in south London.
London Wildlife Trust launched the Great North Wood project in 2017, supported by Heritage Lottery Fund, and now works with volunteers, community groups, landowners, and councils, to revive and reimagine this ancient landscape as a home for nature and people.
In the woods
A walk through these autumnal woods is a grand tour through an explosion of colour. Hues of yellow, red, brown and green can be seen in varying combinations as leaves flutter gently down to carpet the woodland floor. But why have the leaves turned yellow? In fact, why were they ever green in the first place?
Our schooldays taught us how plants use chlorophyll to produce energy using sunlight, but chlorophyll has a ‘green gap’ – it uses the red and blue parts of the colour spectrum but green is reflected back unused. Chlorophyll is so ubiquitous in leaves that it masks other pigments that are always present. As the chlorophyll is broken down and recycled by the tree in autumn, these hidden carotenoids and anthocyanins are unmasked and show their fiery array of reds and yellows.
In the Great North Wood it is the hornbeam that steals the autumnal show. Beneath a browning oak ceiling, the delicate yellows of the hornbeam float over foundations of waxy, evergreen holly. The female holly bushes join in the colour party in the storeys above, with their adornment of festive red berries. This scene is best viewed in Dulwich Wood and Sydenham Hill Wood, close to the border between the two woods that is demarcated by a row of green wooden posts.
Stools of hazel also provide a splash of yellow throughout the Great North Wood, particularly in Beaulieu Heights, a wonderful wood off South Norwood Hill. With its more unusual mix of species, Hillcrest Wood offers opportunities to see rowans going a riotous red or sweet chestnuts presenting an autumnal palette on their outsized leaves.
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On the streets
When viewing the Great North Wood landscape from higher ground, it is striking how extensive the tree cover appears to be. Much of this appearance is bolstered by planting of street trees. The pioneers of this rugged existence are the London planes and common limes that the Victorians delighted in planting to fringe their new suburban idyll – the south London that they built and we still know today. The mighty planes are somewhat of an autumnal disappointment, their pointed leaves mostly go a crispy brown before they drop to rest in the gutter below, awaiting a final journey in the gusts of a municipal leaf-blower.
The new kid on the block is the sweet gum (below), its flamboyant autumnal reds are clearly fashionable in the latest wave of urban tree planting. Other species currently in vogue for street planting include tuliptree and a ‘living fossil’, the ginkgo. Increasing numbers of youthful individuals of these species are particularly noticeable in the Dulwich area, brightening backstreets that apparently did not warrant an avenue of planes or limes when originally laid out in the 1800s.
In parks and gardens
The Living Landscape of the Great North Wood is not just about the surviving fragments of precious woodland. It is augmented by other green space across the area: parks, gardens, railway linesides, sports pitches and cemeteries. These spaces have a mixture of native woodland tree species and ornamental planting, providing an intriguing autumnal blend. Copper beeches have a disadvantage that humans deliberately selected for - an extension of the ‘green gap’ that means that they are also unable to use red light and therefore reflect that back too. Parks often have the hornbeam cultivar ‘fastigiata’, a dense and low-sprouting version of the woodland original that becomes a furnace of yellow as November comes around.
One autumnal quirk can be found in the resolutely green leaves of alders. They defy the yellowing trend of trees in their vicinity, keeping up a verdant appearance right up to leaf fall. Alders prefer damp environments and aren’t historically associated with the Great North Wood, but have been planted in local parks, such as a new avenue at the south end of Peckham Rye Park (below). Forester Peter Wohlleben suggested in his book The Hidden Life of Trees that since alders have a symbiotic relationship with nitrogen-fixing bacteria in their roots, they may not need to recycle any chlorophyll in autumn and have no trouble in producing it from scratch each year. This gives alders and their bacterial partners a bonus few weeks of photosynthesis, furthering the mutual benefit from their winning enterprise.
Explore the Great North Wood
Whether in woods, parks, gardens or on the streets, autumn is a wonderful time of year to explore the Great North Wood. If you are interested in volunteering with us in woods across the area please get in touch, we always welcome new volunteers. We also regularly run guided walks and talks, click here for upcoming events.
Learn more about our Great North Wood project.
The Great North Wood project is funded by Heritage Lottery Fund, the Mayor of London, Veolia Environmental Trust, Dulwich Estate, and Dulwich Society.
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